1. Field of the Invention
The invention relates to a holding device for a blood sample removal tubule.
2. Description of the Prior Art
Holding devices for blood sample removal tubules of a blood removal device are known from WO 89/10723, for example, which has a receiving vessel for a front end of the blood sample removal tubule. The blood sample removal tubule is closed at its front end by a closure device. In the receiving vessel, a needle holder is arranged for a cannula, which projects in the direction of an opened front side of the receiving vessel and the through opening of which is connected with a removal needle of a needle arrangement via a connecting canal constructed between the needle holder and the front wall of the receiving vessel. This removal needle is arranged eccentrically to a central longitudinal axis of the receiving chamber. Between the connecting canal and a receiving chamber of the receiving vessel, a valve arrangement is provided which is able to be opened as required. This valve arrangement is formed by the cannula and the needle holder. For this, the cannula is mounted so as to be adjustable in a bore of the needle holder in the longitudinal direction of the central longitudinal axis of the receiving vessel. To limit the adjustment movement, the cannula is provided in its end arranged in the connecting canal with a stop projecting over its outer periphery in a radial direction. For this, the cannula is squeezed together in its end facing the connecting canal and is bent around through 90.degree. and has in the side wall an opening through which the through-flow opening is connected in a conducting manner with the connecting canal. A disadvantage here is that through the cannula mounted displaceably in the needle holder, the gas tightness between the removal needle and the blood sample removal tubule can only be achieved with difficulty and in addition to permeability, which partially also leads to an emergence of the blood, in many cases the vacuum of the blood sample removal tubule can not be used for the removal of blood.
Further blood removal devices are known from U.S. Pat. No. 4,819,659, European patents 0 478 459; 0 286 087 and 0 364 777, in which the cannula is constructed in each case so as to be continuous and is mounted in a needle holder or in a guide sleeve. In so doing, the cannula represents at the same time at one end the removal needle and at the other end the puncture needle into the closure plug of the blood sample tubule. In addition, the cannula is surrounded at the end facing the blood sample removal tubule with a valve arrangement, which is able to be opened as required, in the form of a hose valve. In these embodiments of the removal device, it is not possible to separate the holding device from the needle arrangement in order, for example, to be able to supply an infusion to the patient, without having to remove the needle. Furthermore, an increased safety risk exists for the user in that owing to the already fixedly arranged removal needle, injuries can already occur during the preparation of the holding device. An additional disadvantage is also produced by the fact that the removal needle, which is constructed so as to be continuous, is arranged centrally to the holding device, whereby owing to the greater inclined position of the entire removal device on piercing into the vein, an increased additional risk of injury exists.